Electronic Supplementary Information

Star-shaped discotic compounds with tetrazole and oxadiazole

fragments

Nadezhda V. Usol’tseva, Olga B. Akopova, Antonina I. Smirnova,

Maria I. Kovaleva, Natalia V. Bumbina, Nataliia V. Zharnikova

Nanomaterials Research Institute, Ivanovo State University, Ivanovo, Russia

E-mail: nv_usoltseva@mail.ru

Molecular parameters

Molecular parameters (MP) are relative values and they were calculated as follows:

1. The planarity of the molecule:

K = Lmax / s,

where Lmax is the maximum length of the molecule, taking into account that the

hydrocarbon radicals are in the stretched trans-conformation, s is the thickness of the

molecule.

2. Symmetry of the central fragment:

Kс = bc / lc,

where bc is the width of the central fragment, lc is the length of the central fragment.

3. Contribution of the peripheral part of the molecule with respect to the central part:

Kp = lc / 2lp,

where lc is the length of the central fragment, lp is the length of the peripheral part of the

molecule.

4. The degree of substitution of the central fragment of the molecule:

Ks = Ns /Nmax,

where Ns is the number of substituted positions, Nmax is the maximum possible number

of substituents attached to the selected central fragment.

5. Molecular mass parameter:

Mm = Mc / Mp,

where Mc is the molecular mass of the central fragment of the molecule, Mр is molecular

weight of the peripheral substituents.

6. Reduced molecular mass parameter: Mr = Мm · Ks.

7. Density of the periphery of molecule (the packing density of peripheral substituents):

Kar = Np / ( lp2 + lp lc),

where Np is the number of carbon, hydrogen and other atoms surrounding the central

part, lp and lc are the lengths of the central and the peripheral fragments, respectively

(taking into account that hydrocarbon radicals are in the stretched trans-conformation).

Table 3. Molecular parameters and mesomorphism prediction for the homologues of

pyrromelitic acid with tetrazole fragments (5a)

n Е, kcal/mol Mm Mr Kp K Kar P

6 97.57 2.43 1.61 1.30 5.92 0.093 7 99.26 2.08 1.39 1.13 7.31 0.090 8 101.06 1.82 1.22 1.00 7.76 0.087 9 102.92 1.62 1.08 0.90 8.20 0.084 10 104.72 1.46 0.98 0.81 8.62 0.081 11 106.60 1.33 0.89 0.74 9.05 0.079 12 108.44 1.22 0.81 0.68 9.49 0.076

n – homologue number, P – prediction of mesomorphism, typical for discotic mesogens; Ks = 0.67 – for all homologues of 5a; Kс = 4.22–4.24.

Table 4. Molecular parameters and mesomorphism prediction for the homologues of

pyromellitic acid with oxadiazole fragments (5b)

n Е, kcal/mol Mm Mr Kp K Kar P1 82.31 0.81 0.54 0.60 4.11 0.151 2 81.73 0.71 0.48 0.52 4.45 0.146 +3 83.89 0.64 0.43 0.45 5.80 0.138 +4 85.72 0.58 0.39 0.40 6.19 0.132 +5 87.61 0.53 0.35 0.36 6.72 0.124 +6 89.48 0.49 0.32 0.36 7.27 0.138 +7 91.26 0.45 0.30 0.30 8.00 0.113 +8 93.09 0.42 0.28 0.28 8.60′ 0.109 9 94.90 0.40 0.26 0.26 9.04′ 0.104 10 96.74 0.37 0.25 0.24 9.52 0.100 11 98.60 0.35 0.23 0.22 10.07 0.093 12 100.46 0.33 0.22 0.21 10.17 0.092

n – homologue number, P – prediction of mesomorphism, typical for discotic mesogens; Ks = 0.67 – for all homologues of 5b; Kc = 3.10–3.20

Table 5. Molecular parameters and mesomorphism prediction for the homologues of

cyanuric acid with tetrazole fragments (6a)

n Е, kcal/mol Mm Mr Kp K Kar Р2 53.21 6.41 6.41 2.24 4.58 0.10 –3 55.18 4.32 4.32 1.66 4.85 0.10 –4 57.09 3.26 3.26 1.30 5.31 0.10 –5 59.01 2.62 2.62 1.08 5.65 0.10 –6 60.91 2.19 2.19 0.91 6.18 0.09 –7 63.80 1.88 1.88 0.79 6.58 0.09 –8 66.14 1.64 1.64 0.70 7.08 0.08 –9 68.83 1.46 1.46 0.63 7.53 0.08 –10 71.59 1.32 1.32 0.57 7.79 0.07 –11 74.28 1.20 1.20 0.52 7.97 0.07 –12 76.98 1.20 1.20 0.48 8.38 0.07 –

n – homologue number, P – prediction of mesomorphism, typical for discotic mesogens; Ks = 1.00 – for all homologues of 6a; Kc = 1.01

Table 6. Molecular parameters and mesomorphism prediction for the homologues of

cyanuric acid with oxadiazole fragments (6b)

n Е, kcal/mol Mm Mr Kp K Kar Р2 79.59 1.53 0.51 1.03 2.78 0.08 –3 81.49 1.37 0.46 0.88 2.80 0.08 –4 83.40 1.24 0.41 0.78 2.70 0.07 –5 85.33 1.13 0.38 0.69 2.81 0.07 –6 87.26 1.04 0.35 0.63 2.73 0.07 –7 89.26 0.97 0.33 0.57 2.85 0.07 –8 91.19 0.90 0.30 0.53 2.76 0.06 –9 93.11 0.84 0.28 0.49 2.90 0.06 ±

10 95.11 0.79 0.27 0.46 2.81 0.06 +11 97.02 0.75 0.25 0.43 2.88 0.06 +12 98.87 0.71 0.24 0.40 2.84 0.06 +

n – homologue number, P – prediction of mesomorphism, typical for discotic mesogens; Ks = 0.33 – for all homologues of 6b; Kc = 1.34–1.43

Table 7. Molecular parameters and mesomorphism prediction for the homologues of

5,5'-azo-bis-isophthalic acid with tetrazole fragments (7a)

n Е, kcal/mol Mm Mr K Kp Kar P1 102.74 15.47 15.47 6.49 12.88 0.16 –2 103.83 8.01 8.01 4.73 6.47 0.14 –3 107.48 5.40 5.40 6.76 4.01 0.12 –4 111.09 4.07 4.07 5.22 2.97 0.11 –5 114.66 3.27 3.27 4.99 2.32 0.09 –6 118.45 2.73 2.73 4.58 1.93 0.09 –7 122.04 2.35 2.35 4.64 1.63 0.09 –8 125.62 2.05 2.05 3.84 1.43 0.08 –9 129.54 1.83 1.83 4.21 1.25 0.08 –10 133.12 1.65 1.65 3.59 1.13 0.08 –11 136.75 1.50 1.50 3.74 1.02 0.08 –12 140.34 1.32 1.32 3.29 0.94 0.075 –

n – homologue number, P – prediction of mesomorphism, typical for discotic mesogens; Ks = 1.00 – for all homologues of 7a; Kc = 1.13

Table 8. Molecular parameters and mesomorphism prediction for the homologues of

5,5'-azo-bis-isophthalic acid with oxadiazole fragments (7b)

n Е, kcal/mol Mm Mr K Kp Kar P1 115.66 1.05 0.35 15.65 1.22 0.15 –2 116.57 0.93 0.31 12.76 1.11 0.16 –3 120.27 0.83 0.28 7.15 0.87 0.13 –4 124.33 0.75 0.25 4.52 0.76 0.12 +5 128.11 0.69 0.23 4.09 0.67 0.12 +6 131.72 0.63 0.21 3.83 0.60 0.11 +7 135.33 0.59 0.19 3.73 0.55 0.11 +8 139.59 0.55 0.18 2.85 0.52 0.11 +9 143.25 0.51 0.17 2.70 0.46 0.09 +10 146.86 0.48 0.16 2.61 0.43 0.09 +11 150.79 0.45 0.15 2.34 0.40 0.09 +12 154.47 0.43 0.14 2.23 0.37 0.09

n – homologue number, P – prediction of mesomorphism, typical for discotic mesogens; Ks = 0.33 – for all homologues of 7b; Kc = 1.18

Table 9. Molecular parameters and mesomorphism prediction for the homologues of

4,4'-azodiphthalic acid with tetrazole fragments (8a)

n Е, kcal/mol Mm Mr K Kp Kar P1 120.56 15.74 2.32 4.42 12.08 0.17 –2 121.98 8.00 1.20 4.42 3.58 0.09 –3 125.49 5.40 0.81 4.19 2.67 0.09 –4 128.99 4.07 0.61 4.21 2.07 0.09 –5 132.65 3.27 0.49 4.22 1.72 0.09 –6 136.25 2.73 0.41 4.21 1.45 0.08 –7 139.83 2.34 0.35 4.16 1.27 0.08 –8 143.51 2.06 0.31 4.04 1.12 0.08 –9 147.09 1.83 0.27 4.01 1.01 0.08 –10 150.78 1.65 0.25 3.91 0.91 0.07 –11 154.35 1.50 0.22 3.30 0.83 0.07 –12 158.03 1.37 0.21 3.82 0.76 0.07 –

n – homologue number, P – prediction of mesomorphism, typical for discotic mesogens; Ks = 0.15 – for all homologues of 8a; Kc = 1.87–2.04

Table 10. Molecular parameters and mesomorphism prediction for the homologues of

4,4'-azodiphthalic acid with oxadiazole fragments (8b)

n Е, kcal/mol Mm Mr K Kp Kar P1 103.85 1.05 0.42 6.71 0.94 0.11 –2 107.24 0.93 0.37 3.00 0.81 0.11 –3 110.76 0.83 0.33 2.74 0.71 0.11 ±4 114.50 0.75 0.30 2.72 0.63 0.11 +5 118.10 0.69 0.28 2.51 0.57 0.10 +6 121.69 0.64 0.25 2.50 0.52 0.14 +7 125.40 0.59 0.24 2.36 0.47 0.09 +8 129.02 0.55 0.22 2.38 0.44 0.09 +9 132.61 0.51 0.20 2.22 0.40 0.09 +10 136.10 0.48 0.19 2.23 0.38 0.08 +11 139.83 0.46 0.18 2.10 0.35 0.08 +12 143.39 0.43 0.17 2.10 0.33 0.08 +

n – homologue number, P – prediction of mesomorphism, typical for discotic mesogens; Ks = 0.40 – for all homologues of 8b; Kc = 2.30–2.35

Fig. 6. Screenshot of the СMP ChemCard program

Table 11. Molecular parameters and mesomorphism prediction for the homologues of

triphenylene derivatives (9d)

n Е, kcal/mol Mm Mr Kp K Kar P

1 579.97 0.79 0.39 0.81 2.23 0.119 ±2 583.99 0.76 0.38 0.79 2.02 0.113 ±3 588.67 0.73 0.37 0.73 2.37 0.109 +4 590.80 0.71 0.35 0.72 2.53 0.102 +5 598.70 0.68 0.34 0.68 2.70 0.098 +6 602.38 0.66 0.33 0.66 3.07 0.097 +7 607.80 0.64 0.32 0.62 3.41 0.094 +8 611.92 0.62 0.31 0.60 2.96 0.090 +9 618.72 0.60 0.30 0.57 2.73 0.088 +10 622.73 0.59 0.29 0.54 2.43 0.086 +11 626.36 0.57 0.28 0.52 2.93 0.084 +12 633.87 0.56 0.28 0.50 3.12 0.081 +

n – homologue number, P – prediction of mesomorphism, typical for discotic mesogens; Ks = 0.50 – for all homologues of 9d; Kc = 1.00–1.04

Table 12. Molecular parameters and mesomorphism prediction for the homologues of

triphenylene derivatives (9e)

m Е, kcal/mol Mm Mr Kp K Kar P

2 280.07 0.26 0.26 0.49 2.23 0.26 +

4 332.05 0.34 0.34 0.61 2.22 0.22 +

6 341.06 0.41 0.41 0.77 2.29 0.20 +

8 350.55 0.49 0.49 0.92 2.22 0.18

10 364.48 0.57 0.57 1.10 2.53 0.16

12 375.88 0.64 0.64 1.25 2.05 0.14 m – length of flexible spacer, P – prediction of mesomorphism, typical for discotic mesogens; Ks = 0.67 – for all homologues of 9e; Kc = 4.22–4.24

Synthetic procedure and material characterization

2-N-hexyl-5-(4-hydroxyphenyl)tetrazole 11

A mixture of 5-(4-hydroxyphenyl) tetrazole (2.0 g; 0.0123 mol), hexyl bromide (1.7 ml;

0.0122 mol), anhydrous potassium carbonate (6.0 g; 0.043 mol), dibenzo-18-crawn-6

(1.5 g; 0.042 mol) in dry DMF (50 ml) was stirred at room temperature during 3 days

(including 15 hours of vigorous stirring). Then, the reaction mixture was filtered and the

residue was washed several times by DMF. The obtained filtrate was poured into water,

extracted with ether and dried over Na2SO4. After recrystallization from isopropanol the

crude di-substituted compound (11) with melting point 30–33 С was isolated. The

solvent was removed under reduced pressure and the residual oil was treated with

hexane. A white fine-dispersed residue was filtered off and dried to obtain 0.9 g of final

product 11 with melting point103 С. Yield 44 %.

Elemental analysis: ММ = 246.35; С13Н18N4О: found %, С 63.42,H 7.51, N 22.65;

calculated %, С 63.37, H 7.38, N 22.75.

1Н-NMR (500 MHz, CDCl3): 8.06-8.05 (d, 2H, CH-Ar), 6.97-6.96 (d, 2H, CH-Ar), 5.2

(s, OH), 4.6 (t, 2H, -N-CH2-), 2.07 (m, 2H, -CH2-), (m, 6H, -(CH2)3-), 0.9 (t, 3H, -CH3).

5-(4-hexyloxyphenyl)tetrazole 16 (n = 6)

A mixture of 4-hexyloxybenzonitrile 15 (5.55 g; 0.0273 mol), sodium azide (7.1 g;

0.109 mol), ammonium chloride (5.84g; 0.109 mol) in DMF (150 ml) was refluxed

under argon atmosphere during 25 h. The reaction mixture was poured into ice water

(400 ml). The precipitated residue was filtered off, dried and recrystallized from

acetone. The white product 16 with Тmp = 170 С was obtained. Yield 46%.

Elemental analysis: ММ = 246.31; С13Н18N4О: found %, С 63.42,H 7.46, N 22.68;

calculated %, С 63.39, H7.37, N22.75.

1Н-NMR(500 MHz, CDCl3): 7.60-7.59 (d, 2H, CH-Ar), 6.96-6.95 (d, 2H, CH-Ar), 4.01

(t, 2H, -CH2O-), 1.85-1.79 (m, 2H, -CH2-), 1.50-1.34 (m, 6H, -(CH2)3-), 0.92 (t, 3H, -

CH3).

IR spectrum (KBr), cm-1: 3100, 3050 (NH), 2956, 2869 (-СН3), 2930, 2856 (-СН2),

1615 (С=С), 1262 (R-O-R'), 839 (1,4-Ar), 725((-СН2)x).

Benzene-1,2,4,5-tetracarboxy-[tetra-kis(N-hexylphenyl)tetrazole] 5a.

To pyromellitic acid (0.25 g; 0.98 mmol) in dichlorometane (DCM) (30 ml) was added

dicyclohexylcarbodiimide (DCC) (1.6 g) and tetrazole 11 (0.98 g; 3.98 mmol) dissolved

in DCM (15 ml) and catalytic amount of 4-(dimetylamino)pyridine (DMAP). The

mixture was vigorously stirred at room temperature during 40 h. At the final stage of

stirring the temperature of the reaction mixture was raised up to 40 С. The formed

precipitate was filtered off. The filtrate was partially evaporated and chromatographed

on silica gel. The first fraction was taken, solvent evaporated and the residue was treated

several times by isopropanol. 0.15 g of final product of whitish pink colour with Тmp =

136–137 С was obtained. Yield ~ 15%.

Elemental analysis: MM = 1167.32, C62H70N16O8: found %, С 63.43,H 6.24,N 19.43;

calculated %, С 63.79, H 6.06, N 19.20.

1Н-NMR (500 MHz, CDCl3):8.66 (s, 2H, СН-Ar, from central phenyl ring), 8.28-8.26

(dd, 8H, CH-Ar, from a peripheral phenyl ring), 7.46-7.44 (dd, 8H, CH-Ar, from a

peripheral phenyl ring), 4.67 (tt, 8H, -N-CH2-), 2.11-2.06 (m, 8H, -CH2-), 1.42-1.30 (m,

24H, -(CH2)3-), 0.94-0.89 (m, 12H, -CH3)

2,3,5,6-tetra[4-hexyloxyphenyl-2-(1,3,4-oxadiazole)]benzene 5b (n = 6).

Synthesis was carried out in two stages. At first stage pyromellitic acid chloride was

prepared by a modified method [17, 18]. To pyromellitic acid (0.5 g; 0.002 mol) was added

thionyl chloride (12 ml) and catalytic amount of DMF. The reaction mixture was refluxed

during 25 h. Then, thionyl chloride was distilled off and the acid chloride was obtained as a

pale yellow compound that was used without isolation for the next step.

At the second stage, a solution of 5-(4-hexyloxyphenyl) tetrazole 16 (n=6) (3.2 g;

0.0132 mol) in dry pyridine (100 ml) was added dropwise to the flask with acid chloride

under argon flow. The reaction mixture was refluxed during 48 h. Then it was poured on ice

acidified with hydrochloric acid. The precipitate was filtered, washed until neutral and

dried. The product was purified by column chromatography on silica gel (eluent:

chloroform/ethyl acetate, 5:1). 2 g of final product with Тmp=160–162 С was obtained.

Yield 57 %.

Elemental analysis: MM = 1055.29, C62H70N8O8: found %, С 70.33,H 6.58,N 10.49;

calculated %, С 70.57, H 6.69, N 10.62.

1Н NMR(500 MHz, CDCl3): 9.00 (s, 2H, СН-Ar, from central phenyl ring), 7.94-7.93

(dd, 8H, CH-Ar, from a peripheral phenyl ring), 6.95-6.93 (dd, 8H, CH-Ar, from a

peripheral phenyl ring), 4.00-4.03 (tt, 8H, -О-CH2-), 1.84-1.80 (m, 8H, -CH2-), 1.38-

1.36 (m, 24H, -(CH2)3-), 0.95-0.92 (m, 12H, -CH3).

2,3,5,6-tetra[4-dodecyloxyphenyl-2-(1,3,4-oxadiazole)]benzene 5b (n = 12).

The synthetic procedure and purification of 5b (n = 12) is analogous to 5b (n = 6). After

purification 0.7 g of final product with Тmp = 153–155 С was obtained. Yield 26%.

Elemental analysis: MM = 1391.93, C86H118N8O8: found %, С 74.34,H 8.59,N 8.12;

calculated %, С 74.21, H 8.54, N 8.05.

1Н NMR (500 MHz, CDCl3):8.91 (s, 2H, СН-Ar, from central phenyl ring), 7.94-7.92

(dd, 8H, CH-Ar, from a peripheral phenyl ring), 6.95-6.93 (dd, 8H, CH-Ar, from a

peripheral phenyl ring), 4.02 (tt, 8H, -О-CH2-), 1.84-1.79 (m, 8H, -CH2-), 1.4-1.2 (m,

72H, -(CH2)9-), 0.92-0.87 (m, 12H, -CH3).

IR spectrum (KBr), cm-1: 2922, 2852 (-СН2), 1612 (С=С), 1555, 963 (1,3,4-oxadiazole

ring, 1257 (С-O-С'), 839 (1,4-Ar), 740((-СН2)11).